350 DISEASES OF BREATHING. 



becomes infiamed, the lungs will in all probability, participate in 

 the derangement. Hence, broncho-pneumonia, or pleuro-pneu- 

 monia, are found more frequently than pneumonia, pleurisy, or 

 bronchitis in a pure form. I shall briefly describe the respective 

 symptoms of the three last-named diseases, so that the reader may 

 draw his own inferences in Qomplicated cases, which present far too 

 great a variety to admit of detailed description ; and shall, finally, 

 give the general treatment which is applicable to all of them, with 

 such special directions as the symptoms may indicate. 



Generally speaking, these diseases occur in four ways : (1.) By 

 exposure to cold, especially in combination with a damp and 

 draughty condition of the surrounding air, and when the system 

 is over-heated, debilitated, or exhausted from excessive exertion. 

 (2.) By some mechanical irritant, as may happen when a drench of 

 turpentine. and oil "goes the wrong way"; or when the sharp end 

 of a broken rib pierces the lung. (3.) As secondary diseases ; for 

 instance, when the lungs become invaded with the abscesses of 

 glanders. Under this heading may be included embolic pneumonia, 

 as in inflammation of veins (p. 117). This complication some- 

 times follows strangles, and other inflammatory conditions which 

 are accompanied by the formation of pus. (4.) As infective 

 diseases ; when there is strong reason for believing that they are 

 diseases which involve the entire system, and have a local mani- 

 festation in the organs of breathing. The practical considera- 

 tions which bear out this view are as follows, (a) These diseases 

 often assume an epizootic type. (6) They run a regular course of 

 about a week or ten days, (c) The most successful treatment is one 

 based on the theory that the disease is caused by the presence in 

 the system of some virus, to remove which we should consequently 

 direct our efforts, while at the same time we should support the 

 animal's vital powers. 



The word " epizootic '' is applied to animals, in the same manner 

 as '' epidemic " is to men. 



In these diseases, as in all other inflammations, there is an 

 escape of watery fluid (plasma, p. 12) from the vessels of the in- 

 flamed part, which plasma at first becomes solid, and afterwardi^ 

 breaks up, and is more or less removed. 



As an uninstructed observer of these chest disorder^ will often 

 be unable to detect the disease in its first stage — the horse, at tlie 

 outset, usually appearing to him to be simply dull and out of 

 sorts — ^the attack will in many cases have run a part of its course 

 before its existence is suspected. 



Horse owners should remember that of all stables liable to 

 induce chest diseases, ill-ventilated, damp and draughty ones are 

 the worst. 



